Paper is normally produced by continuous machines which, through the delivery of a stock of cellulose fibers and water distributed from headboxes, generate a ply of cellulose material on a forming fabric, which ply is dried and wound in reels of large diameter. These reels are subsequently unwound and rewound to form logs of smaller diameter. The logs are subsequently divided into rolls of dimensions equal to the dimension of the end product. With this technique, rolls of toilet paper, kitchen towels or other tissue paper products are normally manufactured.
Rewinding machines are used to produce convolutely wound rolls or “logs” of web material. Rewinders are used to convert large parent rolls of paper into retail sized rolls and bathroom tissue and paper towels. These rewinding machines typically wind a predetermined length of web material about a tubular winding core normally made of cardboard. These rolls or logs are then cut into a plurality of smaller-size rolls intended for commercial sale and consumer use. The tubular winding core section remains inside each convolutely wound roll of web material. In both cases the end product contains a tubular core made of material different from that forming the roll.
One type of rewinding machine, known as a surface rewinding machine (also referred to herein as a surface winder, or a rewinder), the rotational movement of the tubular core on which the roll or log is formed is provided by peripheral members in the form of rollers or rotating cylinders and/or belts with which the roll or log is kept in contact during formation.
A majority of surface winders are generally comprised of three principle winding rolls that perform the winding process. These rolls are the first winding roller (or upper winding roll (UWR)), the second winding roller (or lower winding roll (LWR)), and the third winding roller (or rider roll (RR)). The respective winding rolls are named due to where or how they contact a winding log. The UWR and LWR contact the winding log on the upper and lower portions respectively and the RR “rides” on the upper portion of the winding log as it increases in diameter as web material is wound thereabout while disposed between the UWR, LWR, and RR. The winding log enters the surface winder and is adhesively attached to the web material to be wound thereabout in a region of compression disposed between the UWR and LWR. The winding log is initially rotated by the UWR in a region disposed between the UWR and a stationary concave core cradle and rotationally translates to a region disposed intermediate the rotating, but stationary, UWR and LWR (known as the winding nest region). The RR contacts the surface of the rotating winding log in the winding nest region and translates away from the UWR and LWR as web material continues to be convolutely wound about the winding log.
Generally, in these surface wind systems, a web material is convolutely wound about a paperboard core having a 1.5″ to 1.7″ diameter and a length that corresponds to the width of the tissue parent roll which comes from the paper machine, usually 65″ to 155″. Several exemplary prior art surface winders (also called ‘rewinders’) are discussed infra.
FIG. 1 shows an exemplary prior art rewinder in which a web material N is fed from a supply parent roll through a perforation group 5 to the winding region of the rewinder. The rewinder has a first winder roller 15, around which the web material N is fed, and a second winder roller 17. The two rollers 15 and 17 each rotate in a counter-clockwise direction. The cylindrical surfaces of rollers 15 and 17 define a nip 19 through which the web material N is fed. A third roller 21 rotates in a counter-clockwise direction. The winder rollers 15, 17 and 21 define the region where the winding of each log is completed. Completed logs are routed along a chute 31 for further processing.
Disposed upstream of the nip 19 is a curved surface or track 33. The curved surface or track 33 and the cylindrical surface of the first winder roller 15 have a constant radius of curvature with its axis is coincident with the axis of the winder roller 15 and defines a channel 39 for the passage of the cores A between the first winder roller 15 and track 33.
The cores are introduced into the channel 39 by means of a conveyor 47. Disposed at regular intervals on the conveyor 47 are pushers 57 each of which picks up a core A. The cores A are removed by the pushers 57 and lifted and transferred, through a gluing unit, generally shown at 61, which may include a tank 63 of glue in which a series of discs 65 rotate. Such gluers are well-known and need not be described in greater detail. Core A is then transported to channel 39 to start the winding of each log.
The first winder roller 15 and the third roller 21 rotate at a peripheral speed equal to the web material N feeding speed, while the second winder roller 17 rotates at a temporary lower peripheral speed to allow the completed log L to be moved towards the chute 31. The core A1 is inserted into the channel 39 by the pusher 57.
As a new leading edge is produced, core A1 starts to rotate due to contact with stationary surface 33 and the rotating cylindrical surface of the winder roller 15. The core moves forward (i.e., downstream) by rolling along surface 33 at a speed equal to half the feeding speed of the web material N. The cross dimension of channel 39, which is slightly less than the diameter of the core A1 generates the friction is necessary for the angular acceleration of the core A1 from zero to the rolling speed, and the adhesion of the web material N to the surface of the core A1, on which glue has been spread by the gluing device 61. The resulting new leading edge is attached to the core A1 and the process continued.
FIG. 2 provides another prior art surface winder having a winding head 100 comprising first winding roller 103, second winding roller 105, and a third winding roller 107. Between the two winding rollers 103 and 105 there is defined a nip 111 for passage of the web material. Log L1 is formed inside the winding cradle defined by the three winding rollers 103, 105 and 107.
The cores A are fed along a feeder 147. Single winding cores A1 are picked up by a core inserter 149 after a longitudinal line of glue has been applied thereto by a glue applicator 151. The glued core is then placed proximate to the concave plate 117 disposed upstream of the nip 111. The path of the web material N1 extends around the first winding roller 103 and inside the channel 119 and then through the nip 111 to feed the web material N1 inside the winding cradle formed by the winding rollers 103, 105 and 107 which then disposed the web material N1 convolutely about the core A1.
FIG. 3 provides another exemplary prior art surface winder suitable for a winding operation of a roll L2 within the winding zone 214. Here, a core 210 having an initial glue 215 applied thereto is conveyed by a carrier 216 of a conveyor (not labeled) to the inlet end 209a of the curved channel 209. A push plate 217 having rotary movement and when contacting the core 210 pushes the core 210 into the curved channel 209. The core 210 is then driven by the first winding roller 204 and rolls forward.
After the web material w is broken, the leading edge w1 is wound around a new core 210 and the trailing edge w2 of the web material w is wound around the previous roll L2. The core 210 is then conveyed to the winding zone 214 to start a next cycle of the winding operation.
FIG. 4 provides still another exemplary prior art surface winder having at least one supply station 304 of support cores 305. The supply station 304 of the support cores 305 is provided with an advancing plane 306 on which abutment elements 307 operatively associated with the advancing plane 306 move the support cores 305 towards a joining and coupling station 308 of the machine 302. At the supply station 304, the machine 302 provides at least one application station 309 of glue 310 to a support core 305.
The application station 309 is provided with a mechanical application device 311 that, through the movement of application blade 312, picks up a predetermined quantity of glue 310 by dipping the application blade 322 into a housing tank 313 and deposits the glue 310 on the outer surface of the support core 305 rolling on the advancing plane 306. The machine 302 transports at least one web material N3 having a plurality of transverse spaced perforation and weakening lines to an outer portion of roller 317.
At conveying station 308, the support cores 305 having glue 310 disposed thereon and the web material N3 converge and contact each other. The web material N3 adheres to the outer surface of a respective support core 305. In short, loading device 318 pushes a respective support core 305 against the web material N3 disposed on the roller 317 so that the glue 310 bonds the respective support core 305 and the web material N3 together. Winding station 322 having two winding rollers 323, 324 then rotate the support core 305 to wind the web material N3 thereabout. Once winding is complete, the web material N3 is broken so that the last sheet of paper can be glued to the log of paper 303 before transfer to a subsequent packaging machine.
As shown in FIG. 5, an exemplary surface winder provides a core C2 retained above the core conveyor by a pivoting arm 438. When the arm 438 pivots to release the core C2, the core C2 is carried to the conveyor 435 by a core support guide 439. A line of adhesive 441 was previously applied to the core by an adhesive applicator 442.
The conveyor 435 deposits the core on an upstream holding portion 443 of the stationary plate 432. The core C3 does not contact the web N4 in the holding position.
When the perforation for the last sheet for the winding log L is just downstream of the core C3, the web N4 is severed at the desired perforation to form a leading edge. Rotation of the pinch arm 446 moves the core C3 so that the core C3 contacts the web N4 and begins to roll on the stationary plate 432. The stationary plate 432 and the holding portion 443 thereof can be provided with slots to permit the axially spaced pinch arms 446 to pass therethrough. As the core rolls on the stationary plate, the line of glue on the core C3 picks up the web N4 slightly upstream of the leading edge of the web N4, the web N4 is transferred to the core C3, and the leading end portion of the web N4 folds back over the outside of the glued portion of the web N4.
The core C3 which begins a new log L can move through the nip between the first winding roll 427 and the second winding roll 428 by moving the second winding roll away from the first winding roll 427 and/or changing the speed of the second winding roll 428 relative to the speed of the first winding roll 427.
As shown in FIG. 6, another exemplary surface winder provides for cores 511 to be picked up by a core inserter 549 after a longitudinal line of glue has been applied thereto by a glue applicator 551. The core inserter 549 translates the winding core 511 having glue disposed thereon to a point of entry into the introductory portion 512 of the surface rewinding machine disposed between the upper winding roll 503 having a web material N5 disposed about at least a portion thereof and the concave cradle 541. The region disposed between concave cradle 541 and upper winding roll 503 is winding cradle 513. The region disposed between leading edge device 514 and upper winding roll 503 forms the introductory portion 512 of winding cradle 513.
The rewinding machine comprises a first winding roller 503, a second winding roller 505, and a third winding roller 507. A nip 515 is defined between the two winding rollers 503 and 505 for passage of the web material to be wound about core A inside the winding cradle defined by the three winding rollers 503, 505 and 507.
However, current surface winders have limitations. For example, the core, prior to being inserted into the winding system, has an adhesive disposed upon it. As noted, the adhesive placed upon the core is intended to contact the web material coming into the UWR and cause it to fixably attach to the core via the adhesive disposed thereupon. The attachment of web material to the core via the core glue is sometimes referred to as core bonding.
The core having the adhesive disposed upon its surface is then mechanically transferred to the surface winding system. However, there are several degrees of freedom with such a system as the core glue is applied to the core, the core is transferred to the winding cradle and then a portion of the web material is then adhesively attached to the core. These numerous degrees of freedom provide a significant opportunity for misalignment, mis-attachment, and/or mis-insertion, etc. of the web material to the adhesive-laden core with such a system.
For example, as shown in FIG. 7, when a core is inserted into the region between the UWR and the cradle prior to insertion into the winding nest area, the core must undergo a transformation where the core surface speed must be accelerated from zero (i.e., has no surface speed at the point of entry) to the surface speed of the UWR (i.e., UWR running speed). In other words, the surface speed of the core is accelerated from zero to the surface speed of the UWR while disposed within the region between the cradle and the UWR. However, it has been observed that several mechanics-related principles in this region of the re-winder act to retard this required surface speed acceleration.
First, the entry portion of the cradle shown in FIG. 8 is positioned at a fixed point disposed orbitally about the UWR and typically has a smooth surface. A typical leading edge device is provided with a surface finish texture that is a generally smooth and polished. Leading edge device is typically affixed to the concave cradle shown in FIG. 7. The placement of a core having zero surface speed into the entry point of the winding cradle and the ensuing contact with the web material in contact with the UWR causes the core to slip (i.e., not spin) against this initial portion of the winding cradle. This slippage is represented by the arrow labeled “S” in FIG. 9. This slippage is believed to cause the core to oblongly deform into an ellipsoid shape.
A leading edge device having a generally smooth and polished finished surface can facilitate the sliding of a winding core disposed within the introductory portion of a winding cradle. Without desiring to be bound by theory, it is believed that winding core initially slips and does not immediately assume a rotational motion as it first contacts the surface of leading edge device and the moving web material having a velocity, ν, contacting upper winding roll. Since the winding core has no rotational surface speed as it first contacts the surface of leading edge device and the moving web material, any adhesive disposed upon the core is now out of rotational position for attachment to the moving web material. For example, the glue-laden core (targeted to contact the web material in contact with the upper winding roll at a predetermined location immediately adjacent a perforation) will not contact the web material at the predetermined location causing several unfavorable results that result in mal-formed final product.
For example, if the web material attachment point to the core occurs at a point removed backwards from the region near a perforation (e.g., behind the perforation) present in web material, any excess leading web material can ‘fold-back’ upon the core and overlap the region of actual attachment of the web material to the core. This causes a consumer undesirable and unattractively wound product.
If the web material attachment point to the core occurs at a point removed forwards from the region near the perforation (e.g., ahead of the perforation) present in web material, the web material can fail to attach to the core. This can result in the adhesive disposed upon the core contacting the manufacturing equipment ultimately resulting in a process shut-down. Not only will the web material need to be re-threaded though the rewinder, but adhesive will also have to be removed from the surfaces of the rewinding equipment such as the winding cradle and UWR.
Net—If the winding core slides through the initial portion of the winding cradle, adhesive disposed upon the core can be deposited upon the surfaces of the rewinder. This is a significant manufacturing issue that can result in a process shut-down to remove adhesive from the surfaces of the rewinder such as first winding roller, second winding roller, third winding roller, concave cradle, winding cradle, and/or leading edge device.
One of skill in the art will understand that when a winding core rolls without slipping, the point of contact of the winding core has zero linear velocity relative to the surface of the leading edge device. When rolling with slipping occurs, the point of contact of winding core with the surface of leading edge device has a non-zero linear velocity relative to the surface of leading edge device. As the winding core effectively slides along (or upon) the surface of the leading edge device, kinetic friction, f, eventually reduces the linear (e.g., non-rotational) velocity of winding core relative to the surface of the leading edge device. This frictional, f, force also causes the winding core to start rotating about its center of mass (cm). The linear velocity along the surface of leading edge device of winding core decreases and the angular velocity, ω, of winding core increases until the non-slip condition νcm=Rω is met. Then winding core rolls upon the surface of the leading edge device about its center of mass without slipping.
To work properly, the linear velocity, ν, of the winding core must always equal the rate of rotation, ω, of the winding core multiplied by the radius, R, of the winding core from the center of rotation to the point of contact of the winding core with the upper winding roll. If the magnitude of the linear velocity at the edge of the rotating winding core does not equal the magnitude of the linear velocity of the center of rotation of the rotating core, then there must be slippage at the point of contact of the core with the upper winding roll or the surface of the leading edge device. This can result in the linear, non-rotating, movement of the core relative to the surface of the leading edge device because the center of rotation/mass of the core must move faster than the rotation of the upper winding roll can move it. The force of friction, f, from the surface of the leading edge device is the only force acting upon the surface of the core to cause the core to reduce its velocity, ν, and increase the rotational velocity of the core to match the surface speed of the upper winding roll and the web material in contacting engagement therewith (e.g., in the rewinder described herein—also ν).
Mathematically stated, at the point of insertion of the winding core into the introductory portion of winding cradle slipping and rolling forward provides νcm<Rω. Thus, the path of the core through the introductory portion of the winding cradle forms a prolate (contracted) cycloid because the traced out points on the surface of the generating circle that is slipping while rolling with νcm<Rω.
Second, the glue-laden core is targeted to contact the web material in at a predetermined location. Typically the targeted location on the web is immediately adjacent a perforation. If this targeted attachment location changes, the aforementioned unfavorable results can occur in the early stage formation of the wound material.
Finally, adhesive disposed upon the core can be deposited upon the surfaces of the rewinding equipment (e.g., the winding cradle and UWR) if the core slides through the initial portion of the winding cradle. This can result in the aforementioned process shut-down to remove adhesive from the surfaces of the rewinding equipment.
Thus, there is a clearly defined need to improve the correlation and placement of adhesive upon a core at a point that is closer to the point of insertion into the winding cradle, or placed upon the core within the winding cradle, to prevent the drawbacks observed by current surface winding equipment that meets current manufacturing financial and processing targets. This can provide a closer association of the position upon the core where the adhesive is disposed thereupon with the web material that is intended to be contacted thereto. This can also greatly simplify current surface winder architecture by eliminating for the external core glue application and core translation systems.